The present invention relates to an ionographic chamber of the type known from U.S. Pat. No. 3,828,192.
With high-pressure ionography chambers, a gas layer, which is heavy in comparison with low-pressure chambers, i.e., of about 1 cm, is being used. As a rule, this layer is curved spherically so that the electric lines of force coincide with the direction of incident rays. As is well known in the art, rays used in radiography, particularly X-rays, emanate from a point and propagate spherically in all directions so that the section used for a picture has rays along spherical radii. Due to the curvature of the gas layer, the length of the ray paths in the chamber becomes the same at all points, so that a uniform image may be expected. In order to obtain the charge images that are conventional in ionography, an electrically insulating sheet or foil is placed in front of one of the electrodes in the direction of the opposite electrode. Therefore, this foil also must have the curved shape. It is difficult to achieve a pleat-free adherence to the electrode. With the prior art arrangement mentioned above, complex holding means are provided, which include a number of clamping strips pre-tensioned by springs. The construction is such that these clamping strips first grasp the sheet foil which then is stretched.
It is, therefore, an object of the present invention to avoid, in an ionographic chamber in accordance with the present invention, complex constructions for the curved attachment of the image picture foil and to use the design elements absolutely necessary for the chamber.
Another object of the present invention is to provide an ionographic chamber of the foregoing character which may be economically fabricated and readily maintained in service.
A further object of the present invention is to provide an ionographic chamber, as described, which has a substantially long operating life.